Brachytherapy procedures for the treatment of cancer use radioactive sources placed in or close to tumors. There has been a rebirth of this treatment technique with the advent of high dose-rate computer controlled brachytherapy. This technique can deliver very high doses in a short period of time. The source is driven to the tumor through a catheter or through a series of catheters. The radiation from the source can damage tissue, but has a very sharp fall off as you move away from the source.